Multi-stage planetary transmissions can be used in wind turbines for stepping up the rotational movement of a rotor to which wind is admitted in order to drive a generator for generating electrical energy. Since higher-power planetary transmissions of this kind are exposed to high loads during operation, a sufficiently reliable supply of oil to the bearings inside the transmission should be ensured. If a plurality of transmission stages are coupled together by a spline, the region of the spline should also be adequately lubricated and rinsed with oil in order to reliably remove wear particles from the region of the spline.
EP 2 280 193 A2 discloses a multi-stage planetary transmission for industrial applications, in which an input-side first planetary stage is coupled to a downstream second planetary stage by a spline. The spline is formed by an end external toothing on the sun shaft of the first planetary stage which engages with an internal toothing, corresponding thereto, in a receiving bushing of the planet carrier. The spur gear stage on the transmission output side is connected downstream of the second planetary stage, which spur gear stage is also coupled via a spline.
In order to supply lubricating oil to the bearings inside the transmission and to the splines, an intricate network of oil conducting channels inside the transmission is provided, which channels are interconnected in part and are formed in the planet carriers, the connecting shafts and on fixed housing portions using intermediate rotary transmission leadthroughs. For example, the region of the spline between the second planetary stage and the spur gear stage on the transmission output side is guided via an oil supply channel that passes axially through an input shaft of the spur gear stage, an adjoining pipe expansion joint, to the lubricant supply channel portion in the region of the receiving bushing of the spline. At the end, lubricating oil is supplied via a nozzle which sprays lubricating oil in a direction oblique to the spline. Rinsing of the spline region with a high lubricating oil flow rate cannot be achieved by this solution. Moreover, the intricate network of oil conducting channels inside the transmission requires significant manufacturing outlay.
EP 2 199 607 A2 discloses a generic multi-stage planetary transmission that uses fewer and shorter oil conducting channels for supplying oil to the planetary gear bearings of the two planetary stages and to the intermediate spline compared with the prior art discussed above. For this purpose, an oil supply channel is provided that is fixed in the transmission housing and is connected, by means of a plurality of oil conducting channels guided through one of the side faces of the planet carrier, to oil conducting channels that are guided through the shafts of all the planetary gears and are open towards the planetary gear bearings. In this case, the fixed oil supply channel penetrates an insert ring fastened thereto, which ring is L-shaped in cross section and on the radial limb of which an upper rotary transmission leadthrough to the planet carrier of the first planetary stage, rotating relative thereto, is formed. A further rotary transmission leadthrough to the planet carrier of the second planetary stage is formed on the underside of the radial portion. Said further rotary unit opens into a further oil conducting channel on the side of the planet carrier of the second planetary stage, which channel finally opens into the region of the planetary gear bearings of the second planetary stage in order to lubricate said bearings. In contrast, the spline between the two planetary stages is formed by a spray head that extends in the radial direction and is attached to a horizontal portion of the insert ring. Effective rinsing of the region of the spline cannot be achieved by this technical solution either.